<template>
  <div>
      <h4>子组件：{{ value }}</h4>
      <button @click="addFn"> + </button>
  </div>
</template>

<script>
export default {
  props: {
    value: Number
  },
  methods: {
    addFn () {
      this.$emit('input')
    }
  }
}
</script>

<style>

</style>
